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Per Hellstrand - One of the best experts on this subject based on the ideXlab platform.

  • MicroRNAs are essential for stretch-induced vascular smooth muscle contractile differentiation via miR-145-dependent expression of L-type calcium channels
    The Journal of biological chemistry, 2012
    Co-Authors: Karolina M. Turczyńska, Karl Swärd, Per Hellstrand, Mardjaneh Karbalaei Sadegh, Sebastian Albinsson
    Abstract:

    Abstract Stretch of the vascular wall is an important stimulus to maintain smooth muscle contractile differentiation that is known to depend on L-type calcium influx, Rho-activation, and actin polymerization. The role of microRNAs in this response was investigated using tamoxifen-inducible and smooth muscle-specific Dicer KO mice. In the absence of Dicer, which is required for microRNA maturation, smooth muscle microRNAs were completely ablated. Stretch-induced contractile differentiation and Rho-dependent Cofilin-2 phosphorylation were dramatically reduced in Dicer KO vessels. On the other hand, acute stretch-sensitive growth signaling, which is independent of influx through L-type calcium channels, was not affected by Dicer KO. Contractile differentiation induced by the actin polymerizing agent jasplakinolide was not altered by deletion of Dicer, suggesting an effect upstream of actin polymerization. Basal and stretch-induced L-type calcium channel expressions were both decreased in Dicer KO portal veins, and inhibition of L-type channels in control vessels mimicked the effects of Dicer deletion. Furthermore, inhibition of miR-145, a highly expressed microRNA in smooth muscle, resulted in a similar reduction of L-type calcium channel expression. This was abolished by the Ca2+/calmodulin-dependent protein kinase II inhibitor KN93, suggesting that Ca2+/calmodulin-dependent protein kinase IIδ, a target of miR-145 and up-regulated in Dicer KO, plays a role in the regulation of L-type channel expression. These results show that microRNAs play a crucial role in stretch-induced contractile differentiation in the vascular wall in part via miR-145-dependent regulation of L-type calcium channels.

  • Distinct Effects of Voltage- and Store-dependent Calcium Influx on Stretch-induced Differentiation and Growth in Vascular Smooth Muscle
    The Journal of biological chemistry, 2010
    Co-Authors: Jingli Ren, Sebastian Albinsson, Per Hellstrand
    Abstract:

    Stretch of the vascular wall stimulates smooth muscle hypertrophy by activating the MAPK and Rho/Rho kinase (ROK) pathways. We investigated the role of calcium in this response. Stretch-stimulated expression of contractile and cytoskeletal proteins in mouse portal vein was inhibited at mRNA and protein levels by blockade of voltage-dependent Ca(2+) entry (VDCE). In contrast, blockade of store-operated Ca(2+) entry (SOCE) did not affect smooth muscle marker expression but decreased global protein synthesis. Activation of VDCE caused membrane translocation of RhoA followed by phosphorylation of its downstream effectors LIMK-2 and Cofilin-2. Stretch-activated Cofilin-2 phosphorylation depended on VDCE but not on SOCE. VDCE was associated with increased mRNA expression of myocardin, myocyte enhancer factor (MEF) -2A and -2D and smooth muscle marker genes, all of which depended on ROK activity. SOCE increased ERK1/2 phosphorylation and c-fos expression but had no effect on phosphorylation of LIMK-2 and Cofilin-2 or on myocardin and MEF2 expression. Knock-down of MEF2A or -2D eliminated the VDCE-induced activation of myocardin expression and increased basal c-jun and c-fos mRNA levels. These results indicate that MEF2 mediates VDCE-dependent stimulation of myocardin expression via the Rho/ROK pathway. In addition, SOCE activates the expression of immediate-early genes, known to be regulated by MEF2 via Ca(2+)-dependent phosphorylation of histone deacetylases, but this mode of Ca(2+) entry does not affect the Rho/ROK pathway. Compartmentation of Ca(2+) entry pathways appears as one mechanism whereby extracellular and membrane signals influence smooth muscle phenotype regulation, with MEF2 as a focal point. (Less)

  • Distinct Effects of Voltage- and Store-dependent Calcium Influx on Stretch-induced Differentiation and Growth in
    2010
    Co-Authors: Jingli Ren, Sebastian Albinsson, Per Hellstrand
    Abstract:

    Stretch of the vascular wall stimulates smooth muscle hyper- trophy by activating the MAPK and Rho/Rho kinase (ROK) pathways. We investigated the role of calcium in this response. Stretch-stimulated expression of contractile and cytoskeletal proteins in mouse portal vein was inhibited at mRNA and protein levels by blockade of voltage-dependent Ca 2 entry (VDCE). In contrast, blockade of store-operated Ca 2 entry (SOCE) did not affect smooth muscle marker expression but decreased global protein synthesis. Activation of VDCE caused membrane translocation of RhoA followed by phosphorylation of its downstream effectors LIMK-2 and Cofilin-2. Stretch-acti- vated Cofilin-2 phosphorylation depended on VDCE but not on SOCE. VDCE was associated with increased mRNA expression of myocardin, myocyte enhancer factor (MEF) -2A and -2D, and smooth muscle marker genes, all of which depended on ROK activity. SOCE increased ERK1/2 phosphorylation and c-Fos expression but had no effect on phosphorylation of LIMK-2 and Cofilin-2 or on myocardin and MEF2 expression. Knockdown of MEF2A or -2D eliminated the VDCE-induced activation of myocardin expression and increased basal c-Jun and c-Fos mRNA levels. These results indicate that MEF2 mediates VDCE- dependent stimulation of myocardin expression via the Rho/ ROK pathway. In addition, SOCE activates the expression of immediate-early genes, known to be regulated by MEF2 via Ca 2 -dependent phosphorylation of histone deacetylases, but this mode of Ca 2 entry does not affect the Rho/ROK pathway. Compartmentation of Ca 2 entry pathways appears as one mechanism whereby extracellular and membrane signals influ- ence smooth muscle phenotype regulation, with MEF2 as a focal point.

  • Stretch of the Vascular Wall Induces Smooth Muscle Differentiation by Promoting Actin Polymerization
    The Journal of biological chemistry, 2004
    Co-Authors: Sebastian Albinsson, Ina Nordström, Per Hellstrand
    Abstract:

    Stretch of the vascular wall by the intraluminal blood pressure stimulates protein synthesis and contributes to the maintenance of the smooth muscle contractile phenotype. The expression of most smooth muscle specific genes has been shown to be regulated by serum response factor and stimulated by increased actin polymerization. Hence we hypothesized that stretch-induced differentiation is promoted by actin polymerization. Intact mouse portal veins were cultured under longitudinal stress and compared with unstretched controls. In unstretched veins the rates of synthesis of several proteins associated with the contractile/cytoskeletal system (alpha-actin, calponin, SM22alpha, tropomyosin, and desmin) were dramatically lower than in stretched veins, whereas other proteins (beta-actin and heat shock proteins) were synthesized at similar rates. The cytoskeletal proteins gamma-actin and vimentin were weakly stretch-sensitive. Inhibition of Rho-associated kinase by culture of stretched veins with Y-27632 produced similar but weaker effects compared with the absence of mechanical stress. Induction of actin polymerization by jasplakinolide increased SM22alpha synthesis in unstretched veins to the level in stretched veins. Stretch stimulated Rho activity and phosphorylation of the actin-severing protein Cofilin-2, although both effects were slow in onset (Rho-GTP, >15 min; Cofilin-P, >1 h). Cofilin-2 phosphorylation of stretched veins was inhibited by Y-27632. The F/G-actin ratio after 24 h of culture was significantly greater in stretched than in unstretched veins, as shown by both ultracentrifugation and confocal imaging with phalloidin/DNase I labeling. The results show that stretch of the vascular wall stimulates increased actin polymerization, activating synthesis of smooth muscle-specific proteins. The effect is partially, but probably not completely, mediated via Rho-associated kinase and Cofilin downstream of Rho.

Sebastian Albinsson - One of the best experts on this subject based on the ideXlab platform.

  • MicroRNAs are essential for stretch-induced vascular smooth muscle contractile differentiation via miR-145-dependent expression of L-type calcium channels
    The Journal of biological chemistry, 2012
    Co-Authors: Karolina M. Turczyńska, Karl Swärd, Per Hellstrand, Mardjaneh Karbalaei Sadegh, Sebastian Albinsson
    Abstract:

    Abstract Stretch of the vascular wall is an important stimulus to maintain smooth muscle contractile differentiation that is known to depend on L-type calcium influx, Rho-activation, and actin polymerization. The role of microRNAs in this response was investigated using tamoxifen-inducible and smooth muscle-specific Dicer KO mice. In the absence of Dicer, which is required for microRNA maturation, smooth muscle microRNAs were completely ablated. Stretch-induced contractile differentiation and Rho-dependent Cofilin-2 phosphorylation were dramatically reduced in Dicer KO vessels. On the other hand, acute stretch-sensitive growth signaling, which is independent of influx through L-type calcium channels, was not affected by Dicer KO. Contractile differentiation induced by the actin polymerizing agent jasplakinolide was not altered by deletion of Dicer, suggesting an effect upstream of actin polymerization. Basal and stretch-induced L-type calcium channel expressions were both decreased in Dicer KO portal veins, and inhibition of L-type channels in control vessels mimicked the effects of Dicer deletion. Furthermore, inhibition of miR-145, a highly expressed microRNA in smooth muscle, resulted in a similar reduction of L-type calcium channel expression. This was abolished by the Ca2+/calmodulin-dependent protein kinase II inhibitor KN93, suggesting that Ca2+/calmodulin-dependent protein kinase IIδ, a target of miR-145 and up-regulated in Dicer KO, plays a role in the regulation of L-type channel expression. These results show that microRNAs play a crucial role in stretch-induced contractile differentiation in the vascular wall in part via miR-145-dependent regulation of L-type calcium channels.

  • Distinct Effects of Voltage- and Store-dependent Calcium Influx on Stretch-induced Differentiation and Growth in Vascular Smooth Muscle
    The Journal of biological chemistry, 2010
    Co-Authors: Jingli Ren, Sebastian Albinsson, Per Hellstrand
    Abstract:

    Stretch of the vascular wall stimulates smooth muscle hypertrophy by activating the MAPK and Rho/Rho kinase (ROK) pathways. We investigated the role of calcium in this response. Stretch-stimulated expression of contractile and cytoskeletal proteins in mouse portal vein was inhibited at mRNA and protein levels by blockade of voltage-dependent Ca(2+) entry (VDCE). In contrast, blockade of store-operated Ca(2+) entry (SOCE) did not affect smooth muscle marker expression but decreased global protein synthesis. Activation of VDCE caused membrane translocation of RhoA followed by phosphorylation of its downstream effectors LIMK-2 and Cofilin-2. Stretch-activated Cofilin-2 phosphorylation depended on VDCE but not on SOCE. VDCE was associated with increased mRNA expression of myocardin, myocyte enhancer factor (MEF) -2A and -2D and smooth muscle marker genes, all of which depended on ROK activity. SOCE increased ERK1/2 phosphorylation and c-fos expression but had no effect on phosphorylation of LIMK-2 and Cofilin-2 or on myocardin and MEF2 expression. Knock-down of MEF2A or -2D eliminated the VDCE-induced activation of myocardin expression and increased basal c-jun and c-fos mRNA levels. These results indicate that MEF2 mediates VDCE-dependent stimulation of myocardin expression via the Rho/ROK pathway. In addition, SOCE activates the expression of immediate-early genes, known to be regulated by MEF2 via Ca(2+)-dependent phosphorylation of histone deacetylases, but this mode of Ca(2+) entry does not affect the Rho/ROK pathway. Compartmentation of Ca(2+) entry pathways appears as one mechanism whereby extracellular and membrane signals influence smooth muscle phenotype regulation, with MEF2 as a focal point. (Less)

  • Distinct Effects of Voltage- and Store-dependent Calcium Influx on Stretch-induced Differentiation and Growth in
    2010
    Co-Authors: Jingli Ren, Sebastian Albinsson, Per Hellstrand
    Abstract:

    Stretch of the vascular wall stimulates smooth muscle hyper- trophy by activating the MAPK and Rho/Rho kinase (ROK) pathways. We investigated the role of calcium in this response. Stretch-stimulated expression of contractile and cytoskeletal proteins in mouse portal vein was inhibited at mRNA and protein levels by blockade of voltage-dependent Ca 2 entry (VDCE). In contrast, blockade of store-operated Ca 2 entry (SOCE) did not affect smooth muscle marker expression but decreased global protein synthesis. Activation of VDCE caused membrane translocation of RhoA followed by phosphorylation of its downstream effectors LIMK-2 and Cofilin-2. Stretch-acti- vated Cofilin-2 phosphorylation depended on VDCE but not on SOCE. VDCE was associated with increased mRNA expression of myocardin, myocyte enhancer factor (MEF) -2A and -2D, and smooth muscle marker genes, all of which depended on ROK activity. SOCE increased ERK1/2 phosphorylation and c-Fos expression but had no effect on phosphorylation of LIMK-2 and Cofilin-2 or on myocardin and MEF2 expression. Knockdown of MEF2A or -2D eliminated the VDCE-induced activation of myocardin expression and increased basal c-Jun and c-Fos mRNA levels. These results indicate that MEF2 mediates VDCE- dependent stimulation of myocardin expression via the Rho/ ROK pathway. In addition, SOCE activates the expression of immediate-early genes, known to be regulated by MEF2 via Ca 2 -dependent phosphorylation of histone deacetylases, but this mode of Ca 2 entry does not affect the Rho/ROK pathway. Compartmentation of Ca 2 entry pathways appears as one mechanism whereby extracellular and membrane signals influ- ence smooth muscle phenotype regulation, with MEF2 as a focal point.

  • Stretch of the Vascular Wall Induces Smooth Muscle Differentiation by Promoting Actin Polymerization
    The Journal of biological chemistry, 2004
    Co-Authors: Sebastian Albinsson, Ina Nordström, Per Hellstrand
    Abstract:

    Stretch of the vascular wall by the intraluminal blood pressure stimulates protein synthesis and contributes to the maintenance of the smooth muscle contractile phenotype. The expression of most smooth muscle specific genes has been shown to be regulated by serum response factor and stimulated by increased actin polymerization. Hence we hypothesized that stretch-induced differentiation is promoted by actin polymerization. Intact mouse portal veins were cultured under longitudinal stress and compared with unstretched controls. In unstretched veins the rates of synthesis of several proteins associated with the contractile/cytoskeletal system (alpha-actin, calponin, SM22alpha, tropomyosin, and desmin) were dramatically lower than in stretched veins, whereas other proteins (beta-actin and heat shock proteins) were synthesized at similar rates. The cytoskeletal proteins gamma-actin and vimentin were weakly stretch-sensitive. Inhibition of Rho-associated kinase by culture of stretched veins with Y-27632 produced similar but weaker effects compared with the absence of mechanical stress. Induction of actin polymerization by jasplakinolide increased SM22alpha synthesis in unstretched veins to the level in stretched veins. Stretch stimulated Rho activity and phosphorylation of the actin-severing protein Cofilin-2, although both effects were slow in onset (Rho-GTP, >15 min; Cofilin-P, >1 h). Cofilin-2 phosphorylation of stretched veins was inhibited by Y-27632. The F/G-actin ratio after 24 h of culture was significantly greater in stretched than in unstretched veins, as shown by both ultracentrifugation and confocal imaging with phalloidin/DNase I labeling. The results show that stretch of the vascular wall stimulates increased actin polymerization, activating synthesis of smooth muscle-specific proteins. The effect is partially, but probably not completely, mediated via Rho-associated kinase and Cofilin downstream of Rho.

Pekka Lappalainen - One of the best experts on this subject based on the ideXlab platform.

  • Cofilin-2 controls actin filament length in muscle sarcomeres.
    Developmental cell, 2014
    Co-Authors: Elena Kremneva, Maarit Hannele Makkonen, Aneta Skwarek-maruszewska, Gergana Gateva, Alphée Michelot, Roberto Dominguez, Pekka Lappalainen
    Abstract:

    ADF/Cofilins drive cytoskeletal dynamics by promoting the disassembly of "aged" ADP-actin filaments. Mammals express several ADF/Cofilin isoforms, but their specific biochemical activities and cellular functions have not been studied in detail. Here, we demonstrate that the muscle-specific isoform Cofilin-2 promotes actin filament disassembly in sarcomeres to control the precise length of thin filaments in the contractile apparatus. In contrast to other isoforms, Cofilin-2 efficiently binds and disassembles both ADP- and ATP/ADP-Pi-actin filaments. We mapped surface-exposed Cofilin-2-specific residues required for ATP-actin binding and propose that these residues function as an "actin nucleotide-state sensor" among ADF/Cofilins. The results suggest that Cofilin-2 evolved specific biochemical and cellular properties that allow it to control actin dynamics in sarcomeres, where filament pointed ends may contain a mixture of ADP- and ATP/ADP-Pi-actin subunits. Our findings also offer a rationale for why Cofilin-2 mutations in humans lead to myopathies.

  • the three mouse actin depolymerizing factor Cofilins evolved to fulfill cell type specific requirements for actin dynamics
    Molecular Biology of the Cell, 2002
    Co-Authors: Maria K. Vartiainen, Pieta K Mattila, Pauli J Ojala, Irma Thesleff, Tuija Mustonen, Juha Partanen, Pekka Lappalainen
    Abstract:

    Actin-depolymerizing factor (ADF)/Cofilins are essential regulators of actin filament turnover. Several ADF/Cofilin isoforms are found in multicellular organisms, but their biological differences have remained unclear. Herein, we show that three ADF/Cofilins exist in mouse and most likely in all other mammalian species. Northern blot and in situ hybridization analyses demonstrate that Cofilin-1 is expressed in most cell types of embryos and adult mice. Cofilin-2 is expressed in muscle cells and ADF is restricted to epithelia and endothelia. Although the three mouse ADF/Cofilins do not show actin isoform specificity, they all depolymerize platelet actin filaments more efficiently than muscle actin. Furthermore, these ADF/Cofilins are biochemically different. The epithelial-specific ADF is the most efficient in turning over actin filaments and promotes a stronger pH-dependent actin filament disassembly than the two other isoforms. The muscle-specific Cofilin-2 has a weaker actin filament depolymerization activity and displays a 5-10-fold higher affinity for ATP-actin monomers than Cofilin-1 and ADF. In steady-state assays, Cofilin-2 also promotes filament assembly rather than disassembly. Taken together, these data suggest that the three biochemically distinct mammalian ADF/Cofilin isoforms evolved to fulfill specific requirements for actin filament dynamics in different cell types.

  • The Three Mouse Actin-depolymerizing Factor/Cofilins Evolved to Fulfill Cell-Type–specific Requirements for Actin Dynamics
    Molecular Biology of the Cell, 2002
    Co-Authors: Maria K. Vartiainen, Pieta K Mattila, Pauli J Ojala, Irma Thesleff, Tuija Mustonen, Juha Partanen, Pekka Lappalainen
    Abstract:

    Actin-depolymerizing factor (ADF)/Cofilins are essential regulators of actin filament turnover. Several ADF/Cofilin isoforms are found in multicellular organisms, but their biological differences have remained unclear. Herein, we show that three ADF/Cofilins exist in mouse and most likely in all other mammalian species. Northern blot and in situ hybridization analyses demonstrate that Cofilin-1 is expressed in most cell types of embryos and adult mice. Cofilin-2 is expressed in muscle cells and ADF is restricted to epithelia and endothelia. Although the three mouse ADF/Cofilins do not show actin isoform specificity, they all depolymerize platelet actin filaments more efficiently than muscle actin. Furthermore, these ADF/Cofilins are biochemically different. The epithelial-specific ADF is the most efficient in turning over actin filaments and promotes a stronger pH-dependent actin filament disassembly than the two other isoforms. The muscle-specific Cofilin-2 has a weaker actin filament depolymerization activity and displays a 5-10-fold higher affinity for ATP-actin monomers than Cofilin-1 and ADF. In steady-state assays, Cofilin-2 also promotes filament assembly rather than disassembly. Taken together, these data suggest that the three biochemically distinct mammalian ADF/Cofilin isoforms evolved to fulfill specific requirements for actin filament dynamics in different cell types.

  • The three mouse actin-depolymerizing factor/Cofilins evolved to fulfill cell-type-specific requirements for actin dynamics
    Molecular biology of the cell, 2002
    Co-Authors: Maria K. Vartiainen, Pieta K Mattila, Pauli J Ojala, Irma Thesleff, Tuija Mustonen, Juha Partanen, Pekka Lappalainen
    Abstract:

    Actin-depolymerizing factor (ADF)/Cofilins are essential regulators of actin filament turnover. Several ADF/Cofilin isoforms are found in multicellular organisms, but their biological differences have remained unclear. Herein, we show that three ADF/Cofilins exist in mouse and most likely in all other mammalian species. Northern blot and in situ hybridization analyses demonstrate that Cofilin-1 is expressed in most cell types of embryos and adult mice. Cofilin-2 is expressed in muscle cells and ADF is restricted to epithelia and endothelia. Although the three mouse ADF/Cofilins do not show actin isoform specificity, they all depolymerize platelet actin filaments more efficiently than muscle actin. Furthermore, these ADF/Cofilins are biochemically different. The epithelial-specific ADF is the most efficient in turning over actin filaments and promotes a stronger pH-dependent actin filament disassembly than the two other isoforms. The muscle-specific Cofilin-2 has a weaker actin filament depolymerization activity and displays a 5-10-fold higher affinity for ATP-actin monomers than Cofilin-1 and ADF. In steady-state assays, Cofilin-2 also promotes filament assembly rather than disassembly. Taken together, these data suggest that the three biochemically distinct mammalian ADF/Cofilin isoforms evolved to fulfill specific requirements for actin filament dynamics in different cell types.

Pankaj B. Agrawal - One of the best experts on this subject based on the ideXlab platform.

  • knockin mouse model of the human cfl2 p a35t mutation results in a unique splicing defect and severe myopathy phenotype
    Human Molecular Genetics, 2020
    Co-Authors: Samantha M Rosen, Mugdha Joshi, Alan H. Beggs, Talia Hitt, Pankaj B. Agrawal
    Abstract:

    : Cofilin-2 is an actin-binding protein that is predominantly expressed in skeletal and cardiac muscles and belongs to the AC group of proteins which includes Cofilin-1 and destrin. In humans, Cofilin-2 (CFL2) mutations have been associated with congenital myopathies that include nemaline and myofibrillar myopathy. To understand the pathogenicity of the human CFL2 mutation, p.A35T, that first linked Cofilin-2 with the human disease, we created a knock-in mouse model. The Cfl2A35T/A35T (KI) mouse were indistinguishable from their wild-type littermates at birth, but they rapidly worsened and died by postnatal day 9. The phenotypic, histopathologic and molecular findings mimicked the constitutive Cfl2-knockout (KO) mice described previously, including sarcomeric disruption and actin accumulations in skeletal muscles and negligible amounts of Cofilin-2 protein. In addition, KI mice demonstrated a marked reduction in Cfl2 mRNA levels in various tissues including skeletal muscles. Further investigation revealed evidence of alternative splicing with the presence of two alternate transcripts of smaller size. These alternate transcripts were expressed at very low levels in the wild-type mice and were significantly upregulated in the mutant mice, indicating that pre-translational splicing defects may be a critical component of the disease mechanism associated with the mutation. Evidence of reduced expression of the full-length CFL2 transcript was also observed in the muscle biopsy sample of the patient with p.A35T mutation.

  • Skeletal Muscle MicroRNA and Messenger RNA Profiling in Cofilin-2 Deficient Mice Reveals Cell Cycle Dysregulation Hindering Muscle Regeneration
    PloS one, 2015
    Co-Authors: Sarah U. Morton, Mugdha Joshi, Talia Savic, Alan H. Beggs, Pankaj B. Agrawal
    Abstract:

    Congenital myopathies are rare skeletal muscle diseases presenting in early age with hypotonia and weakness often linked to a genetic defect. Mutations in the gene for Cofilin-2 (CFL2) have been identified in several families as a cause of congenital myopathy with nemaline bodies and cores. Here we explore the global messenger and microRNA expression patterns in quadriceps muscle samples from cofillin-2-null mice and compare them with sibling-matched wild-type mice to determine the molecular pathways and mechanisms involved. Cell cycle processes are markedly dysregulated, with altered expression of genes involved in mitotic spindle formation, and evidence of loss of cell cycle checkpoint regulation. Importantly, alterations in cell cycle, apoptosis and proliferation pathways are present in both mRNA and miRNA expression patterns. Specifically, p21 transcript levels were increased, and the expression of p21 targets, such as cyclin D and cyclin E, was decreased. We therefore hypothesize that deficiency of Cofilin-2 is associated with interruption of the cell cycle at several checkpoints, hindering muscle regeneration. Identification of these pathways is an important step towards developing appropriate therapies against various congenital myopathies.

  • Congenital myopathy caused by a novel missense mutation in the CFL2 gene.
    Neuromuscular disorders : NMD, 2012
    Co-Authors: Charlotte W. Ockeloen, Pankaj B. Agrawal, Alan H. Beggs, H.j. Gilhuis, Rolph Pfundt, Erik-jan Kamsteeg, A. Dara Hama-amin, Adinda Diekstra, Nine V A M Knoers, Martin Lammens
    Abstract:

    Nemaline myopathy and myofibrillar myopathy are heterogeneous myopathies that both comprise early-onset forms. We present two sisters from a consanguineous Iraqi Kurdish family with predominant axial and limb girdle weakness. Muscle biopsies showed features of both nemaline myopathy and myofibrillar myopathy. We performed homozygosity mapping in both siblings using an Affymetrix 250K Nspl SNP array. One of the overlapping homozygous regions harbored the gene CFL2. Because a mutation in CFL2 was identified in a family with nemaline myopathy, we performed sequence analysis of the gene and a novel homozygous missense mutation in exon 2 (c.19G>A, p.Val7Met) of CFL2 was identified in both siblings. CFL2 encodes the protein Cofilin-2, which plays an important role in regulation of sarcomeric actin filaments. To our knowledge, this is the second family in which a mutation in CFL2 causes an autosomal recessive form of congenital myopathy with features of both nemaline and myofibrillar myopathy. Given the clinical variability and the multitude of histological features of congenital myopathies, CFL2 sequence analysis should be considered in patients presenting with an autosomal recessive form of congenital myopathy.

  • Normal myofibrillar development followed by progressive sarcomeric disruption with actin accumulations in a mouse Cfl2 knockout demonstrates requirement of Cofilin-2 for muscle maintenance
    Human molecular genetics, 2012
    Co-Authors: Pankaj B. Agrawal, Mugdha Joshi, Talia Savic, Zoe Chen, Alan H. Beggs
    Abstract:

    Cofilin-2, a small actin-binding protein and member of the AC protein family that includes Cofilin-1 and destrin, is predominantly expressed at sarcomeres in skeletal and cardiac muscles. The role of Cofilin-2 in muscle development and function is unclear. In humans, recessive Cofilin-2 mutations have been associated with nemaline myopathy with minicores. To investigate the functional role of Cofilin-2 in vivo, we generated constitutive and muscle-specific Cofilin-2-deficient mice using a cre-loxP strategy. Cofilin-2-deficient mice were similar to their wild-type (WT) littermates at birth, but died by day 8. They were significantly smaller, severely weak and had very little milk in their stomachs. The sarcomeric structure was intact at birth, but by Day 7, skeletal muscles showed severe sarcomeric disruptions starting at the Z-line, along with filamentous actin accumulations consistent with a lack of actin depolymerization activity. Cofilin-2-deficient muscles contained elevated numbers of slow fibers and exhibited upregulation of slow fiber-specific genes. Increased amounts of other sarcomeric proteins including α-actinin-2, α-sarcomeric actin and tropomyosin were also present. While destrin was not expressed in either WT or Cofilin-2-deficient muscles, Cofilin-1 was similarly expressed in developing myofibers of both genotypes. There was no evidence for compensatory changes in expression of either family member in Cofilin-2-deficient tissues. The onset of pathology and weakness in Cofilin-2-deficient muscles correlated with normal developmental loss of Cofilin-1 expression within myofibers, suggesting that Cofilin-1 serves as an early developmental sarcomeric isoform. Overall, Cofilin-2, although not critical for muscle development, is essential for muscle maintenance.

  • Nemaline myopathy with minicores caused by mutation of the CFL2 gene encoding the skeletal muscle actin-binding protein, Cofilin-2.
    American journal of human genetics, 2006
    Co-Authors: Pankaj B. Agrawal, Carina Wallgren-pettersson, Rebecca S. Greenleaf, Kinga K. Tomczak, Vilma-lotta Lehtokari, William Wallefeld, Nigel G. Laing, Basil T. Darras, Sutherland K. Maciver, Philip R. Dormitzer
    Abstract:

    Nemaline myopathy (NM) is a congenital myopathy characterized by muscle weakness and nemaline bodies in affected myofibers. Five NM genes, all encoding components of the sarcomeric thin filament, are known. We report identification of a sixth gene, CFL2, encoding the actin-binding protein muscle Cofilin-2, which is mutated in two siblings with congenital myopathy. The proband's muscle contained characteristic nemaline bodies, as well as occasional fibers with minicores, concentric laminated bodies, and areas of F-actin accumulation. Her affected sister's muscle was reported to exhibit nonspecific myopathic changes. Cofilin-2 levels were significantly lower in the proband's muscle, and the mutant protein was less soluble when expressed in Escherichia coli, suggesting that deficiency of Cofilin-2 may result in reduced depolymerization of actin filaments, causing their accumulation in nemaline bodies, minicores, and, possibly, concentric laminated bodies.

Morris Karmazyn - One of the best experts on this subject based on the ideXlab platform.

  • Ginseng (Panax quinquefolius) Attenuates Leptin-Induced Cardiac Hypertrophy through Inhibition of p115Rho Guanine Nucleotide Exchange Factor-RhoA/Rho-Associated, Coiled-Coil Containing Protein Kinase-Dependent Mitogen-Activated Protein Kinase Pathway
    The Journal of pharmacology and experimental therapeutics, 2011
    Co-Authors: Melissa Moey, Asad Zeidan, Venkatesh Rajapurohitam, Morris Karmazyn
    Abstract:

    Leptin is a 16-kDa peptide primarily derived from white adipocytes and is typically elevated in plasma of obese individuals. Although leptin plays a critical role in appetite regulation, leptin receptors have been identified in numerous tissues including the heart and have been shown to directly mediate cardiac hypertrophy through RhoA/ROCK (Ras homolog gene family, member A/Rho-associated, coiled-coil containing protein kinase)-dependent p38 mitogen-activated protein kinase (MAPK) activation; however, the basis for RhoA stimulation is unknown. Rho guanine nucleotide exchange factors (GEFs) catalyze the exchange of GDP for GTP resulting in Rho activation and may be the potential upstream factors mediating leptin-induced RhoA activation and therefore a potential target for inhibition. We investigated the effects of North American ginseng (Panax quinquefolius), reported to reduce cardiac hypertrophy, on RhoA/ROCK and MAPK activation in ventricular cardiomyocytes exposed to leptin (50 ng/ml) and the possible role of p115RhoGEF and p63RhoGEF in these responses. Leptin produced a robust hypertrophic response that was associated with RhoA/ROCK activation resulting in a significant increase in Cofilin-2 phosphorylation and actin polymerization, the latter evidenced by a reduction in the G/F actin ratio. These effects were prevented by ginseng (10 μg/ml). The stimulation of RhoA/ROCK by leptin was associated with significantly increased p115RhoGEF gene and protein expression and exchange activity, all of which were completely prevented by ginseng. The ability of ginseng to prevent leptin-induced activation of RhoA/ROCK was further associated with diminished p38 MAPK activation and nuclear translocation. These results demonstrate a potent inhibitory effect of ginseng against leptin-induced cardiac hypertrophy, an effect associated with prevention of p115RhoGEF-RhoA/ROCK-dependent p38 MAPK activation.

  • Actin Cytoskeleton Dynamics Promotes Leptin-Induced Vascular Smooth Muscle Hypertrophy via RhoA/ROCK- and Phosphatidylinositol 3-Kinase/Protein Kinase B-Dependent Pathways
    The Journal of pharmacology and experimental therapeutics, 2007
    Co-Authors: Asad Zeidan, Ben Paylor, Karly J. Steinhoff, Sabzali Javadov, Venkatesh Rajapurohitam, Subrata Chakrabarti, Morris Karmazyn
    Abstract:

    Obesity is associated with increased leptin production that may contribute to cardiovascular pathology through a multiplicity of effects. Leptin has been shown to contribute to vascular remodeling through various mechanisms, including production of vascular smooth muscle (VSMC) hypertrophy; however, the mechanisms underlying the vascular hypertrophic effect of leptin remain unknown. In the present study, we investigated the contributions of the RhoA/Rho kinase (ROCK) and phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathways, actin dynamics, and the expression of serum-response factor (SRF) in the hypertrophic effects of leptin on vascular tissue. Strips of rat portal vein (RPV) were cultured with or without leptin at 3.1 nM for 1 to 3 days. Leptin significantly increased RhoA activity by 163 ± 20%, whereas phosphorylation of downstream factors, including LIM kinase 1 and Cofilin-2, was increased by 160 ± 25 and 290 ± 25%, respectively. Leptin also significantly phosphorylated Akt by 130 ± 30%, which was inhibited by the PI3K inhibitor 2-(4-morpholinyl)-8-phenyl-4 H -1-benzopyran-4-one (LY294002). RhoA/ROCK and PI3K/Akt activation was associated with a significant increase in RPV wet weight (11 ± 1%), protein synthesis (45 ± 7%), SRF expression (136 ± 11%), and polymerization of actin, as reflected by an increase in the F-/G-actin ratio, effects that were significantly attenuated by a leptin receptor (leptin obese receptor) antibody, the ROCK inhibitor (+)-( R )- trans -4-(1-aminoethyl)- N -(4-pyridyl) (Y-27632) as well as the PI3K inhibitor LY294002. Our results indicate that the activation of RhoA/ROCK and PI3K/Akt plays a pivotal role in leptin signaling, leading to the development of VSMC hypertrophy through a mechanism involving altered actin dynamics.